Rooney has come under fire in the opening weeks of the season, with Mourinho eventually bowing to pressure to drop his captain to the bench for last weekend’s game against Leicester.

United’s 4-1 win against the Premier League champions at Old Trafford appeared to cement the suspicion that Rooney’s days as a key player in Mourinho’s team are over, but former United skipper Keane offered an alternative view in his role as an ITV Sport pundit.

“He will have a huge part to play,” declared Keane. “He has been criticised recently for his performances, but he is still a young age.

“Even though he played a lot of football after starting at a young age of 16 or 17, but he is still a big player for Man Utd. He will have a big part to play over the next year or two.”

Meanwhile, Keane has put Arsenal winger Theo Walcott firmly in his place, after suggesting he needs to prove his recent surge of form can be sustained over the winter months.

Keane was impressed by Arsenal’s 2-0 win over Basel in the Champions League on Wednesday night, but argued that two-goal hero Walcott and the rest of his team-mates still had much to prove on days when the odds are stacked against them.

“It has taken him a while to get settled hasn’t it….ten years at the club,” said Keane, after Walcott claimed in his post match interview that he has now matured at Arsenal.

“Listen, he had had a good week. The guy needs to relax. Try and play well over the next seven, eight, nine months when the real big crunch games come.

“When Arsenal are in the form they were in against Basel, they are a joy to watch. When they are given that much time and that much possession they are fantastic, but the crunch games are coming up over the next few months.

“The cold night are coming in and half the Arsenal players will have their gloves on! Players like Walcott have to do it consistently over the course of a year or two.”